Need advice on boring bars for boring head

motormech1 said:
Thanks for all the replies everyone. I bookmarked all of them. The DBL-202 takes 1/2" bars. I think I'd like to go with an insert type to start out so a dulled or damaged tip won't slow me down much with regrinding. I'll eventually pick up the other types and learn to grind them properly as I have spare time but right now I just need to get things done. I recall someone (@mikey I think) saying he used cobalt bars because they were better for finishing and better for lower speeds than carbide. Another mentioned solid carbide shank insert bars for rigidity. Does anyone make cobalt inserts? Seems like a good idea. Also, what style insert is the most popular with the most choices? I'm looking for one that is as close to a "do-it-all" bar as possible to get started.
Click to expand...

There are many types of choices for an insert material, but I have never heard of a cobalt insert. In the case of a shank, “cobalt” is used interchangeably with HSS. You can certainly find HSS inserts which can excel in (1) sharpness, and (2) use on softer metals.

I recommend that you use carbide (short for “tungsten carbide”) inserts. They are nice & hard.

If you want a carbide insert that is sharp, you can easily find the insert type you need with a 1/64” nose radius. If you don’t need it to be so hard, you can buy uncoated.

You can always ring up Carbide Depot & ask their recommendation. They are very welcome to take your call. Even if you are only buying 5 or 10 inserts, they are happy to look up the part number for the insert you need. Also, Carbide Depot has competitive pricing, excellent service, huge selection, and product knowledge. They also sell boring bars and tool shanks. They are *not* the place to call if you are looking for Made in China level of quality, but you can save made money if you buy their house brand called Carbi-Universal (usually Made in Switzerland).

Carbide Depot Carbide Inserts Boring Bars Toolholders Milling Cutters End Mills Drills Taps

Carbide inserts and cutting tools from name brand manufacturers for sale online at discount prices
www.carbidedepot.com www.carbidedepot.com
 
Last edited:
I just use whatever HSS or tool steel is in my bin and grind my own. I don't like inserts for fly cuts (interrupted) or boring bars (inserts too thick for small diameters). Just good ol' tool steel.

I also like cemented carbide for these tools, they can be ground to shape in a normal fashion and cut very well.
 
I own and have used HSS, HSS/Cobalt, brazed and inserted carbide bars and if I could only have one choice it would be cobalt without a doubt.

Carbide works but you need speed for it to finish well. This is fine for small bores but once you start to extend the head then vibration becomes an issue as centripetal forces build. What do you do when you need a largish bore with an accurate bore with a fine finish but only have carbide bars and a smallish mill?

In contrast, HSS/Cobalt will cut with a really fine finish and is very accurate at much lower speeds. You will find that these bars hold their edges quite well, too. My Borite sets look and cut like new despite being over 25 years old. You only need to flatten their flat surfaces to sharpen them and that is done in seconds. No "grinding" is ever necessary.

There is a place for carbide, mostly in harder materials. When I need accuracy and a fine finish in a larger bore in harder material, I use Micro 100 solid carbide bars. If tolerances are looser or finish is not as critical then I use brazed or inserted carbide.

When the hole diameter is small and speeds can go up than any of these bars will work. It is when the hole ID gets out towards the limit of the head's extension that you run into issues. You don't know when this will happen so I would really consider buying a cobalt set instead of inserted carbide. If your budget cannot handle them then go for a brazed carbide set; Borite makes good ones. Just make sure to hone them before use.

Hope this helps.
 
LMS has a set of M35 (5% cobalt, versus the 8% M42 that mikey linked above) for a good bit less. Just another option. I have the 3/8” shank versions.

littlemachineshop.com

Boring Bar Set, 1/2" Shank, HSS 2682

Boring Bars 2682 Set of ten boring bars, depth ranges from 3/4" to 2 1/4"; Shank diameter 1/2"; One piece M35 5% Solid Cobalt; Hardened and ground to ...
littlemachineshop.com littlemachineshop.com
 
mikey said:
Hope this helps.
Click to expand...
Yes it did, as did everyone's input. Thanks guys! I think I have a better handle on it now. I'll pick up a good insert bar from one of the suggestions posted and some carbide inserts and the cobalt set @mikey recommended. I think that would take care of things nicely for quite a while.
 
Huub Buis said:
I have tried different type of boring bars (HSS, Brazed Widia, carbide insert) and now use a 12 mm lathe inner turning bar fitted with a dcmt070204 insert. The small 0.4 mm tool nose radius reduces the cutting forces. That gives a better result on my not so rigid BF16 hobby desktop mill.
Some examples
Click to expand...
How safe is it to buy from aliexpress do they take PayPal? Just wondering what your thoughts were.
 
Illinoyance said:
In my experience, the import bars with brazed carbide tips work well if I take the time to properly sharpen them.
Click to expand...

So you sharpen them out of the box?

How do you sharpen them?

Regarding indexable boring bars, even the smallest ones will have a pretty large minimum. My smallest indexable boring bar would need at least a 5/16” hole. Something like this can work with smaller holes:

60FBED34-426B-4CE0-9BDC-C8D01BF4FDC4.png

I sure like stubbies!
 
You must log in or register to reply here.
Back
Top